4.                           ECOLOGICAL ASSESSMENT

 

4.1                       Introduction

 

4.1.1                 This Chapter covers ecological issues arising as a consequence of the proposed KT13 stream channelisation works. The objectives of this ecological assessment are as follows:

 

·                     to establish an ecological baseline for the KT13 study area, focusing on key habitats and species present;

 

·                     to assess the ecological impacts of the proposed channelisation works;

 

·                     to detail effective ecological mitigation measures to reduce or eliminate significant impacts;

 

·                     to determine whether residual, post-mitigation impacts are acceptable; and

 

·                     to assess the post-mitigation acceptability of the proposed project.

 

4.2                       Baseline Ecological Conditions

 

4.2.1                 A habitat survey was conducted in an area of 500 m radius around the existing KT13 streamcourse and the proposed project boundary (Figure 4.1). Appendix C shows the form for ecological field surveys. Twelve habitat types were identified within the Study Area :

 

                      bare ground/works in progress;

                      agricultural land;

                      fishpond;

                      hillside grassland;

                      low-lying grassland/fallow land;

                      marsh;

                      orchard/horticultural land;

                      river/stream;

                      shrubland;

                      urban and industrial area;

                      woodland;

                      drainage channel.


4.2.2                 The same habitat types were found during the dry-season and wet-season surveys, but minor seasonal changes were observed in the habitat areas of fallow fields and agricultural lands. Some areas used as agricultural land in the dry season became fallow fields in wet season. No seasonal variation was found in other types of habitat between the dry and wet seasons. Hence, wet-season habitat surveys were considered to represent the baseline conditions of habitats within the Study Area. The areas of each habitat type within the Study Area and Project Area are listed in Table 4.1 and Table 4.2 respectively. Note that the Project Area refers to the proposed alignment which includes the natural stream courses and the proposed channel within the site boundary, whilst the Study Area includes the proposed alignments of the secondary drainage channel KT13 and the surrounding area up to 500 m from the site boundary.

 

Table 4.1

Habitat Types and Areas within the Study Area

 

Habitat type

Area (ha)

%

Bare ground/works in progress

8.70

4.7

Agricultural land

13.32

7.1

Fishpond

2.30

1.2

Hillside grassland

29.44

15.8

Low-lying grassland/fallow land

17.05

9.1

Marsh

1.18

0.6

Orchard/horticultural land

4.66

2.5

River/stream

3.07

1.6

Shrubland

13.50

7.2

Urban/industrial area

64.14

34.4

Woodland

26.69

14.3

Drainage Channel

2.63

1.4

Total

186.68

100

 

 

Table 4.2

Habitat Types and Areas within the Project Area

 

Habitat type

Area (ha)

%

Bare ground/works in progress

0.133

4.32

Fishpond

0.083

2.69

Low-lying grassland/fallow land

0.781

25.35

Marsh

0.009

0.29

Orchard/horticultural land

0.687

22.30

River/stream

1.000

32.46

Urban/industrial area

0.380

12.33

Woodland

0.008

0.26

Total

3.081

100.0

 


Woodlands

 

4.2.3                 Two areas of woodland are present within the Study Area.

 

4.2.4                 A large woodland is established behind Ma On Kong and Ho Pui Villages. It is dominated by Schefflera octophylla, Pinus massoniana, Aporusa chinensis, Celtis sinensis, Bridelia tomentosa, Cinnamomum camphora, Rhus chinensis and Rhus succedanea. The woodland is mainly natural but some modification by afforestation has occurred. Thus, some commonly used species for forestry plantation such as Tristania conferta, (an exotic tree) can also be found within the woodland. The understorey is quite rich in shrubs including Litsea rotundifolia, Ilex graciliflora, Ilex asprella, Phyllanthus cochinchinensis, Berchemia racemosa, Rhodomyrtus tomentosa, Melastoma sanguineum and Rhaphiolepis indica. An insectivorous herb, Drosera spathulata was observed on some damp rock faces. The Ma On Kong woodland is of much ecological importance because of large size, species diversity, and ecological linkage with the Tai Lam Country Park.

 

4.2.5                 A small woodland present near the Ho Pui Egretry (Plate 4.1) is dominated by Euphoria longan, Rhus chinensis, and Ficus hispida. Euphoria longan is a common fruit tree planted by villagers while Ficus hispida and Rhus chinensis are common wild tree species. A Reeve’s Smooth Skink Scincella reevesii was found in this woodland on the day of the habitat survey. Typical species of butterflies in woodland habitats include Cupha erymanthis, Cyrestis thyodamas, Discophora sondaica, etc. were also observed in the patch of woodland close to the egretry.

 

                 Shrublands

 

4.2.6                 Two patches of shrubland are present within the Study Area. One is located behind Ma On Kong Village while another one is located on the hillside east of the toll gate area of the Route 3. The Ma On Kong shrubland (Plate 4.2) is adjacent to the woodland and hence may be of higher ecological importance. The shrub species found are common in (and native to) Hong Kong, including Litsea rotundifolia, Rhodomyrtus tomentosa, Berchemia racemosa, Rhus succedanea, Rhaphiolepis indica, Phyllanthus cochinchinensis, and Wikstroemia indica. The small tree, Aporusa chinensis is also very common in this shrubland. The shrubland east of the toll gate area is isolated from the country park by the Route 3. Dominant plants include Aporusa chinensis, Litsea rotundifolia, Rhodomyrtus tomentosa, Rhus chinensis, Rhus succedanea, Schefflera octophylla, Phyllanthus cochinchinensis, Ficus hirta, Glochidion eriocarpum, Ilex asprella, Macaranga tanarius and Lantana camara. There is dust deposition on the plants at the edge of the shrubland since it is very close to some construction sites. Other disturbance includes cutting, planting, and burning, mainly caused by grave worshippers during Ching Ming and Chung Yeung Festivals.

 

                 Marsh

 

4.2.7                 One small freshwater marsh (1.2 ha) was found at Ma On Kong (Plate 4.3). It is close to small areas of abandoned fishponds and the woodland behind the village. The dominant wetland species including Colocasia esculenta, Alocasia macrorrhiza, Commelina nudiflora, and Rumex maritimus are common to Hong Kong. Other freshwater plants such as Polygonum hydropiper, Polygonum perfoliatum, Solanum nigrum, Echinochloa crus-galli and Eleusine indica can also be observed occasionally. Several Little Egrets, Egretta garzetta were observed flying over the marsh during the survey.

 

                 Fishponds

 

4.2.8                 Fishponds within the Study Area are very small and scattered. The remaining fishponds located at Ma On Kong are of moderate ecological value as they are linked with a stream, marsh, woodland and some wetland on both sides of the stream and are thus a component of the wetland environs of Ho Pui Egretry. However, the area of these ponds has recently been reduced by filling, considerably decreasing their area and reducing their ecological value, especially as a feeding area for waterbirds. Wetland plants found on the bunds are common species in Hong Kong including Rumex maritimus, Solanum nigrum, Colocasia esculenta, Polygonum hydropiper, Commelina nudiflora, Paspalum sp. and Panicum sp.. Aquatic species, Eichhornia crassipes and Lemna minor were also observed on the water surface of some ponds (Plate 4.4).

 

                 Rivers/Streams

 

4.2.9                 Two streams are present within the Study Area; KT 13 which flows through Ho Pui and KT 12 which passes to the south of Cheung Po. The two streams join the primary drainage channel within the West Rail construction area. All vegetation along these sections has been removed and the path was also being changed. The upper watercourse of KT13 is semi-natural with a length over 800m (Plate 4.5). The water quality is poor with strong odor owing to the discharge of domestic sewage and livestock waste. However, the stream passes through the Ho Pui Egretry and is associated with ponds nearby to provide a feeding ground for avifauna. During fauna surveys, several Chinese Pond Herons, Ardeola bacchus and one Little Egret, Egretta garzetta were found foraging in the stream. A Checkered Keelback, Xenochrophis piscator was also found swimming in the downstream from the egretry.

4.2.10             A second natural stream section is present within the Study Area, the mid-course of KT12 to the south of Cheung Po village. The water quality of this section of KT12 is quite good and a locally rare fish Hongkong Bitterling Rhodeus ocellatus is present in this section of the stream. Wetland plants observed include Commelina nudiflora, Solanum nigrum, Alocasia macrorrhiza, Microstegium ciliatum, and Cyperus alternifolius. An ecological evaluation of KT12 and the impacts of proposed channelisation of this stream has been detailed elsewhere (BBV 2002).

 

Low-Lying Grasslands/Fallow Land

 

4.2.11             Twelve areas of low-lying grassland/fallow field (Plate 4.6) are present within the Study Area, of which two are moderate in size (4-5 ha) and others are small. The two moderate sized low-lying grasslands/fallow fields located south of the village are very close to the egretry, and thus are of higher ecological importance. The dominant plants species are common in abandoned paddy fields, including Solanum nigrum, Amaranthus spinosus, Panicum maximum, Panicum paludosum, Commelina nudiflora, Eleusine indica, Gnaphalium purpureum, Polygonum perfoliatum, Alocasia macrorrhiza, Ageratum conyzoides, Microstegium ciliatum, Colocasia esculenta, Ipomoea cairica, Mikania micrantha, Rumex maritimus, Polygonum chinense, Hedychium coronarium, etc. A notable species of butterfly Danaid Eggfly (Hypolimnas misippus) was seen in disused agricultural land close to the pig farms at the southern end of the site.

 

                 Hillside Grasslands

 

4.2.12             Several areas of hillside grassland are present within the Study Area (Plate 4.7). Various kind of common grass were found, such as Miscanthus floridulus, Imperata cylindrica, Arundinella setosa, Microstegium ciliatum, Bothriochloa intermedia, Rhynchelytrum repens, Setaria pallide-fusca, etc. A common hillside fern, Dicranopters linearis was also observed. This grassland is a plageoclimax maintained by hillfires.

 

                 Agricultural Lands

 

4.2.13             Several areas of agricultural land are present within the Study Area, of which one is large (over 7 ha) and others are small (about 1 ha). The largest one is located around the Cheung Po village (Plate 4.8). The common crops in these cultivated fields are vegetables such as Ipomoea aquatica, Lactuca sativa and flowers such as Gladiolus gandavensis and Lilium longiflorum. Some fruit trees were also observed here including, Musa paradisiaca, Euphoria longan, and Prunus persica. This type of habitat is widespread in Hong Kong, as well as South China.

                 Orchard/Horticultural Lands

 

4.2.14             Three small orchards are present within the Study Area. Common fruit trees Euphoria longan, Litchi chinensis, and Clausena lansium can be found (Plate 4.9). The Ma On Kong egretry is situated in the smallest patch of orchard, to the northwest of the proposed alignment.

 

4.2.15             The horticultural land is located at Ma On Kong village. Both native and exotic ornamental plants can be found, including Araucaria heterophylla, Chrysalidocarpus lutescens, Livistonia chinensis, Caryota ochlandra, Podocarpus macrophyllus, Bauhinia blakeana, Ficus benjamina, Ficus rumphii, Erythrina speciosa, etc.

 

                 Urban and Industrial Areas (UIA)/Bare Ground/Works In Progress

 

4.2.16             UIA includes villages, roads, animal farmhouses and the Route 3 highway. A large site for the West Rail occupies the area from Cheung Po to Pat Heung Road.

 

Drainage Channel

 

4.2.17             The Study Area (but not the Project Area) contains recently constructed concrete-lined drainage channels supporting little or no flora and fauna.

 

4.3                       Floral Survey Results

 

                 Overall Species Survey

 

4.3.1                 A total of 205 floral species were recorded within the Study Area, of which 155 are native to Hong Kong, and the other 50 are exotic species (Floral list is given in Appendix E). Aporusa chinensis, Bridelia tomentosa, Celtistetrandra, Cinnamomum camphora, Pinus massoniana, Rhus chinensis, Rhus succedanea, and Schefflera octophylla are the most common tree species present in the woodlands. In the low-lying area, Euphoria longan and Musa paradisiaca are the most abundant trees planted by the villagers for their fruits, while Ficus hispida is the most common wild tree species. An exotic species of Central America origin, Lantana camara is the most common shrub found within the Study Area. Although it is not a native species, it is a valuable food plant for butterflies. Mikania micrantha, an aggressive climber, is common. Like Lantana camara, this is also an exotic species and it is now spreading throughout the SAR. Other common climbers include Ipomoea cairica, Polygonum chinense, and Polygonum perfoliatum.

4.3.2                 Three species protected under the Forestry Regulations, Michelia alba, Michelia figo, and Rhododendron championae were found during the floral surveys. All of these species are outside the works area. Michelia alba (Plate 4.10) and Michelia figo (Plate 4.11) were present in the villages of Cheung Po, Ho Pui, and Ma On Kong. These are not naturally occurring but planted by the villagers for amenity purposes. These two species are not included in the floral list as the habitat in which they are located is of low ecological importance. A group of azaleas, Rhododendron championae (Plate 4.12) were found within the shrubland on the hillside behind Ho Pui. These azaleas are far from the Project Area and therefore not expected to be affected by the proposed works. A large banyan tree Ficus tinctoria located in Ho Pui is at least 60 years old. Its location is about 40 to 50 m away from the boundary of the Project Area. It is neither a rare nor protected species. Because of the resistant nature of this species, it is not expected to be affected by the proposed channelization works upstream.

 

4.3.3                 No rare/protected species or species of conservation importance were found within the Project Area and the dominant floral species observed included Bidens pilosa, Cynodon dactylon, Ipomoea cairica, Mimosa pudica, Commelina nudiflora, Alocasia macrorrhiza, Amaranthus spinosus, Panicum maximum, Panicum paludosum, Microstegium ciliatum, Mikania micrantha, Solanum nigrum, and Ipomoea cairica. Ficus hispida and Lantana camara are the most common tree and shrub species found within the Project Area respectively.

 

                 Transect Survey

 

4.3.4                 Along the transect placed in the upstream-section alignment, a total of nine and ten species were encountered in five quadrats placed along the transects during dry- and wet-season surveys respectively (Table 4.3a). The transect ran along the stream section that is within the Project Area (Figure 4.2). The common riparian grass, Panicum maximum had the highest percentage cover, 32% and 26% respectively in both seasons. Ficus hispida is the most abundant tree species found along the stream.

 


Table 4.3a

Belt Transect Floral Survey Results (Upstream Section)

 

Species

Coverage (%)

Dry Season

Wet Season

Amaranthus viridis

2.0

1.0

Bidens pilosa

1.0

3.0

Boehmeria nivea

NP

2.0

Cuscuta chinensis

0.4

NP

Eleusine indica

NP

1.0

Ficus hispida

6.0

2.0

Lantana camara

NP

2.0

Microstegium ciliatum

8.6

23.0

Mikania micrantha

5.0

13.0

Panicum maximum

32.0

26.0

Panicum paludosum

7.0

10.0

Solanum nigrum

16.0

NP

Total

78.0

83.0

 

Note:

1. The percentage values = the mean of the five quadrats

2. NP = not present

 

4.3.5                 In the mid-section alignment, the habitat type was low-lying grassland. A total of 14 and 15 species were recorded during the dry- and wet-season surveys respectively (Table 4.3b). Bidens pilosa, Cynodon dactylon, Ipomoea cairica, Mimosa pudica and Urena lobata were the most common species occupying the grassland.

 

Table 4.3b

Belt Transect Floral Survey Results (Mid-Section)

 

Species

Coverage (%)

Dry Season

Wet Season

Amaranthus viridis

0.4

0.6

Bidens pilosa

2.0

1.8

Bothriochloa ischaemum

NP

0.2

Pueraria phaseoloides

NP

0.2

Cuscuta chinensis

0.1

NP

Cynodon dactylon

1.5

1.4

Digitaria sanguinalis

0.4

0.4

Eleusine indica

0.8

0.6

Erechthites hieraciifolia

NP

0.4

Erigeron floribundus

0.4

0.6

Ipomoea cairica

70

75

Lantana indica

0.1

NP

Mikania micrantha

0.8

0.6

Mimosa pudica

5.5

8.0

Sesbania cochinchinensis

0.2

0.2

Sida rhombifolia

0.2

0.2

Urena lobata

1.5

1.6

Total

83.9

91.8

 

Note:

1. The percentage values = the mean of the five quadrats

2. NP = not present

 

4.3.6                 The two transect surveys showed that similar vegetation composition between different seasons and all flora species found were very common and typical species throughout the HKSAR.

 

4.4                       Fauna Survey Results

 

                 Bird, Amphibian & Reptile, Mammal, Insects, Aquatic Invertebrates and Fish Surveys

 

4.4.1                 Faunal surveys accordingly to the methodology shown in Table 4.4 were conducted on during the period from April to July 2000, as is detailed in Table 4.5. The bird, amphibian, reptile, mammal and insects surveys essentially covered the area 300m from the proposed channel in accordance with the EIA Study Brief. Reference is made to study of active egret nests in August 2000 by Kwok et al (2001). The findings indicate that there were no active nests in Ma On Kong in August 2000.

 

                 Overall Fauna Survey Results

 

(i)         Birds

 

A total of 27 bird species was recorded in an extended survey to a radius of 300 m from the discharge points at KT13 (see Table 4.5a). These included three raptors seen flying over the site: Crested Serpent Eagle and Bonelli’s Eagle on 22 May, and Eurasian Hobby on 10 April. This compares with a total of 45 species recorded during the Hong Kong Bird Watching Society (HKBWS) breeding bird survey (Carey et al. 2001). Results from the two surveys are presented and compared in Table 4.4. Note, however, that the 1 km square which includes most of the Study Area also includes part of the Shek Kong catchwater forest on the hills above. Thus, a number of forest species were recorded in the 1 km square during the HKBWS survey which would not be expected in the present Study Area.

For species where breeding was not proven, likely status is based on Carey et al. (2001), Kwok and Corlett (1999) for forest species, Leven (1998) for farmland species and Leven (2001) for shrubland species. Percentage of 1 km squares in Hong Kong in which a species was present is derived from Carey et al. (2001).

 

Table 4.4

Faunal Surveys of KT13 – Summary of Methodologies

 

Faunal Group

Survey Dates

Time / Duration

Methodology

Birds – general surveys

25.05.00
26.05.00
30.05.00
22.06.00

1000-1400h
1000-1400h
1000-1400h
1000-1400h

The entire Study Area of KT13, including areas up to a distance of 300m from the discharge points, was walked on four separate dates during the period May-June 2000, and all wetland-associated birds which were seen utilizing the Study Area (i.e. foraging or perching, but not flying over) were identified with the aid of 8 x 32 binoculars.

Birds – breeding ardeids

10.04.00
30.04.00
22.05.00
26.05.00
22.06.00
26.06.00
01.07.00
16.07.00

0730-0930h
0730-0930h
0730-0930h
0730-0930h
0730-0930h
0730-0930h
0730-0930h
0730-0930h

The two egretries at Ho Pui and Ma On Kong were visited at least once per month in the early morning during the period April to July 2000. During each visit, the following data were collected for each ardeid species present:: number of adults present, number of active nests, number of juveniles, and size of obvious broods. Observations were made with 10 x 50 or 8 x 40 binoculars.

Birds – ardeid flight-lines

29.05.00
03.06.00
14.06.00
23.06.00
01.07.00

0600-1100h
0600-1100h
0600-1100h
0600-1100h
0600-1100h

Observations of flight lines were made from the Shek Kong Water Catchment road on the south side of the valley. This was 80 m above sea level, and as such allowed excellent views of the valley. Observations commenced at or close to dawn, and continued for five hours. This was to coincide with the period of peak activity, which has been shown to significantly higher in the early morning (Young 1993). Observations were made with 10 x 50 or 8 x 40 binoculars, and a 30 x 70 telescope, and involved following individual adult egrets until they landed at the foraging site. At which point the location at which they landed was recorded using a 1:20,000 map of the study area, and the habitat type selected. If birds flew out of sight before they landed, this was noted, and the location at which they were lost from sight. For data analysis, the distance flown was taken as the point at which the bird was lost from sight. While this results in an under estimate of the average distance flown, it is preferred to ignoring these data which would result in even greater bias as bird lost from sight were not surprisingly, relatively distant when this happened. By excluding these data, the average distance flown would be significantly reduced and this would place greater value on those habitats closer to the egretry.

Mammals

22.05.00

25.05.00
26.05.00
30.05.00
22.06.00

16.07.00

1000-1400h + 1930-2130h
1000-1400h
1000-1400h
1000-1400h
1000-1400h + 1930-2130h
1930-2130h

Non-flying terrestrial mammals were surveyed on four days and three nights during the period May-July 2000. During day-time surveys, mammal signs such as scats, prints and burrows were searched for over the entire Study Area, including up to 300m from the discharge points. Any such signs encountered were recorded and species identification was made based on the surveyor’s knowledge of the signs left by different mammal species in Hong Kong. During night surveys, the surveyor walked the Study Area with a strong flashlight and any mammals encountered were identified on sight.

Reptiles

22.05.00

25.05.00
26.05.00
30.05.00
22.06.00

16.07.00

1000-1400h + 1930-2130h
1000-1400h
1000-1400h
1000-1400h
1000-1400h + 1930-2130h
1930-2130h

Reptiles were surveyed on four days and three nights during the period May-July 2000. During day-time surveys, the entire Study Area, including up to 300m from the discharge points, was walked and the surveyor investigated microhabitats such as piled material, large stones, tree trunks, buildings, drainage channels and the stream channel itself. All reptiles observed were identified in the field, occasionally with the aid of binoculars. During night surveys, the Study Area was walked and foraging reptiles were spotlighted using a strong flashlight, and identified on site.

Amphibians

22.05.00

25.05.00
26.05.00
30.05.00
22.06.00

16.07.00

1000-1400h + 1930-2130h
1000-1400h
1000-1400h
1000-1400h
1000-1400h + 1930-2130h
1930-2130h

Amphibians were surveyed on four days and three nights during the period May-July 2000. During day-time surveys, the entire Study Area, including up to 300m from the discharge points, was walked and the surveyor identified all species observed. During night surveys, the Study Area was walked with a strong flashlight and all amphibians seen were identified. In addition, amphibians were identified from male breeding vocalizations.

Fish

 

09.05.00
15.05.00
12.07.00

Daytime

As the streams are heavily polluted, visual observation was employed.

Butterflies

25.05.00
26.05.00
30.05.00
22.06.00

1000-1400h
1000-1400h
1000-1400h
1000-1400h

Butterflies were surveyed on four days, during the warmest part of the day, during the period May-June 2000. In each survey the entire Study Area, including up to 300m from the discharge points, was walked and all adult butterflies observed were identified. Identifications were facilitated by use of close-focusing 8 x 32 binoculars. A long-handled net was occasionally employed to catch species which required examination in the hand for proper identification.

Dragonflies

25.05.00
26.05.00
30.05.00
22.06.00

1000-1400h
1000-1400h
1000-1400h
1000-1400h

Dragonflies were surveyed on four days, during the warmest part of the day, during the period May-June 2000. In each survey the entire Study Area, including up to 300m from the discharge points, was walked and all adult dragonflies observed were identified. Identifications were facilitated by use of close-focusing 8 x 32 binoculars. A long-handled net was occasionally employed to catch species which required examination in the hand for proper identification.

 


Table 4.5a

Bird Species Recorded in the KT 13 Study Area during the Present Study and in the HKBWS Breeding Bird Survey and Their Probable Status

 

Species

Recorded in:

Per Cent of 1 km squares in HK

Breeding habitat

Likely current status in Study Area*

Common name

Scientific name

Present study

HKBWS breeding survey

Little Grebe

Tachybaptus ruficollis

-

Present

2.8

Fishponds

Former breeder**

Little Egret

Egretta garzetta

Breeding

Breeding

14.5

Tree and bamboo clumps near wetlands

Breeding at egretry

Cattle Egret

Bubulcus ibis

Breeding

Breeding

9.7

Tree and bamboo clumps near wetland agriculture

Breeding at egretry

Chinese Pond Heron

Ardeola bacchus

Breeding

Breeding

21.2

Tree and bamboo clumps near wetlands

Breeding at egretry

Black Baza

Aviceda leuphotes

-

Present

5.5

Forest, forest-shrubland mosaic

Summer visitor in catchwater forest

Black Kite

Milvus migrans

-

Present

37.7

Forest, forest-shrubland mosaic

Casual visitor

Crested Serpent Eagle

Spilornis cheela

One sighting

Present

7.0

Forest

Occasional visitor from forest

Crested Goshawk

Accipiter trivirgatus

-

Breeding

9.6

Forest

Resident in catchwater forest

Bonelli’s Eagle

Hieraaetus fasciatus

One sighting

-

N.A.***

Mountains

Casual visitor

Eurasian Hobby

Falco subbuteo

One sighting

Present

2.1

Scattered trees in grassland

Casual summer visitor

White-breasted Waterhen

Amaunornis phoenicurus

Present

Present

18.2

Wetland, streams

Resident along streams

Rock Dove

Columba livia

-

Present

10.8

Anthropogenic habitats

Resident around settlement

Spotted Dove

Streptopelia chinensis

Present

Present

62.4

Anthropogenic habitats

Resident

Emerald Dove

Chalcophaps indica

-

Present

4.3

Forest, shrubland

Resident in forest, shrubland

Chestnut-winged Cuckoo

Clamator coromandus

-

Present

9.7

Forest, shrubland

Summer visitor in forest, shrubland

Large Hawk Cuckoo

Hierococcyx sparverioides

-

Present

19.7

Forest, fung shui woods

Summer visitor in forest, fung shui woods

Indian Cuckoo

Cuculus micropterus

-

Present

21.1

Forest, shrubland

Summer visitor in forest, shrubland

Common Koel

Eudynamys scolopacea

Present

Present

40.0

Farmland, anthropogenic habitats

Resident

Greater Coucal

Centropus sinensis

Present

Present

31.8

Farmland, grassland

Resident

Lesser Coucal

Centropus benghalensis

-

Present

27.7

Grassland

Resident in grassland

Collared Scops Owl

Otus bakkamoena

-

Present

4.5

Forest, fung shui woods

Resident in forest, fung shui woods

Little Swift

Apus affinis

Present

Present

39.2

Aerial feeder, breeds in towns

Casual visitor

Great Barbet

Megalaima virens

-

Present

6.4

Forest

Resident in catchwater forest

White-Throated Kingfisher

Halcyon smyrnensis

Present

-

21.7

Shrubland, farmland, near wetland and streams

Breeding resident near stream

Barn Swallow

Hirundo rustica

Present

Breeding

50.3

Farmland, anthropogenic habitats

Breeding summer visitor

White Wagtail

Motacilla alba

-

Present

5.8

Farmland

Breeding resident

Red-Whiskered Bulbul

Pycnonotus jocosus

Present

Breeding

71.8

Shrubland, anthropogenic habitats

Breeding resident

Chinese Bulbul

Pycnonotus sinensis

Present

Breeding

87.2

Ubiquitous

Breeding resident

Long-Tailed Shrike

Lanius schach

Present

Breeding

33.8

Farmland, grassland

Breeding resident

Oriental Magpie Robin

Copsychus saularis

Present

Breeding

45.4

Anthropogenic habitats

Breeding resident

Blue Whistling Thrush

Myophonus caeruleus

-

Present

18.9

Forest, shrubland

Breeding resident

Masked Laughingthrush

Garrulax perspicillatus

Present

Breeding

51.2

Farmland, anthropogenic habitats

Breeding resident

Hwamei

Garrulax canorus

-

Present

43.3

Shrubland

Breeding resident in shrubland

Yellow-Bellied Prinia

Prinia flaviventris

Present

Breeding

62.4

Grassland, grassland-shrubland mosaic

 Breeding resident

Plain Prinia

Prinia inornata

-

Present

8.2

Grassland near wetland, wetland

Former resident**

Common Tailorbird

Orthotomus sutorius

Present

Breeding

67.1

Forest, fung shui woods, shrubland

Breeding resident

Great Tit

Parus major

Present

Breeding

37.4

Forest, fung shui woods

Breeding resident

Fork-Tailed Sunbird

Aethopyga christinae

-

Breeding

16.4

Forest, fung shui woods, shrubland

Breeding resident

Japanese White-Eye

Zosterops japonicus

Present

Present

52.9

Forest, fung shui woods, shrubland

Breeding resident

White-Rumped Munia

Lonchura striata

Present

Breeding

11.2

Forest, fung shui woods, shrubland

Breeding resident

Eurasian Tree Sparrow

Passer montanus

Present

****

49.4

Anthropogenic habitats

Breeding resident

Black-Collared Starling

Sturnus nigricollis

Present

Breeding

29.2

Farmland, anthropogenic habitats

Breeding resident

Common Myna

Acridotheres tristis

Breeding

-

2.4

Farmland

Breeding resident

Crested Myna

Acridotheres cristatellus

Present

Breeding

53.1

Farmland, anthropogenic habitats

Breeding resident

Black Drongo

Dicrurus macrocercus

-

Present

32.3

Farmland, anthropogenic habitats

Breeding resident

Blue Magpie

Urocissa eythrorhyncha

-

Breeding

17.4

Forest

Breeding resident

Common Magpie

Pica pica

-

Present

40.0

Anthropogenic habitats

Breeding resident

 

*              Where current status is not qualified by reference to a particular habitat, status refers to the immediate environs of KT 13 (within c. 50 m) and hence a species is likely to be impacted by the development project.

**            Suitable habitat in the Study Area has been destroyed by filling since the HKBWS survey.

***          Exact distribution not published by Carey et al. (2001) for security reasons.

****        Breeding map omitted by Carey et al. (2001) in error.

 

 

4.4.2                 The habitat utilization of this total of 47 species recorded from the Study Area in respect of the habitats present in the Study Area is indicated in Table 4.5b. Note that this Table includes species which are not tied to one habitat hence the totals are more than the total number of species recorded. For example, White Wagtail regularly makes use of streams and favours this habitat but is not dependent upon it.

 

Table 4.5b

Characteristic Habitat Utilization and Status of Bird Species Recorded from the Study Area

 

Habitat type

Resident (probably breeding)

Non-Breeding Visitor

Bare ground / works in progress

0

0

Agricultural land

15

7

Fishpond

10

3

Hillside grassland

6

5

Low-lying grassland / fallow field

10

3

Marsh

4

4

Orchard / horticultural land

27

4

Plantation

11

5

River / stream

7

4

Shrubland

12

8

Woodland

13

4

Mountains*

2

3

 

*Habitat not present in the Study Area

 


4.4.3                 Thus, the majority of bird species recorded in the Study Area are those of anthropogenic habitats (especially cultivated land) or woodland and shrubland. Species in the former category are common and widespread in Hong Kong (see Table 4.5a above) whilst the woodland and shrubland in the Study Area is remote from the development area. Accordingly, those species most likely to suffer adverse impacts which are of conservation significance are those wetland-dependant species which habitually utilize streams and streamside as detailed in Table 4.6.

 

Table 4.6

Wetland Dependent Species Recorded in the Study Area

 

Species

Status in Study Area

Little Egret

Breeding in egretry; limited use of the stream for foraging (see Flight-line study below).

Cattle Egret

Breeding in egretry, feeds in wet agricultural land.

Chinese Pond Heron

Breeding in egretry; limited use of the stream for foraging (see Flight-line study below).

White-breasted Waterhen

Several individuals recorded foraging in the stream; probably dependent on this habitat.

White-throated Kingfisher

Observed in the downstream section of KT 13. May depend on the stream for nesting and, in part, for feeding

           

(ii)        Amphibians and Reptiles

 

Five anurans, five lizards and three snakes were recorded at KT13 and to 300 m from the discharge points, as follows:

 

Asian Common Toad Bufo melanostictus- several individuals spotted both upstream and downstream of the egretry.

 

Günther’s Frog Rana guentheri - present at scattered localities across the Study Area.

 

Paddy Frog Rana limnocharis - present at scattered localities across the Study Area.

 

Brown Tree Frog Polypedates megacephalus - one individual in vegetation beneath the egretry and one on the stream bank vegetation downstream of the egretry.

 

Asiatic Painted Frog Kaloula pulchra - present at scattered localities across the Study Area.

 

Bowring’s Gecko Hemidactylus bowringii - individuals seen on several buildings across the Study Area.

Changeable Lizard Calotes versicolor – recorded in shrubby vegetation beside the road which runs parallel to the west of the downstream section.

 

Chinese Skink Eumeces chinensis - one individual on the path next to the stream, c. 100 m upstream of the egretry.

 

Long-tailed Skink Mabuya longicaudata - one individual on the road beside the egretry; one in Ho Pui village adjacent to the stream.

 

Reeve’s Smooth Skink Scincella reevesii - one individual in woodland beneath the egretry.

 

Checkered Keelback Xenochrophis piscator - one individual swimming in the stream c. 50m downstream of the egretry.

 

Red-necked Keelback Rhabdophis subminiatus – a juvenile seen on a unsurfaced track close to the northern alignment.

 

Chinese Cobra Naja atra - one dead individual on the stream bank close to the egretry (Plate 4.13).

 

All species are common and widespread in Hong Kong (Karsen et al., 1998).

 

(iii)       Mammals

 

A dead Musk Shrew Suncus murinus was found in Ho Pui village on 16 July (Plate 4.14). This species is considered to be common in New Territories villages (Hill & Phillipps, 1981).

 

(iv)       Dragonflies & Damselflies

 

A total of 24 species were recorded across the extended study site (see Table 4.7), the most notable records being those of the stream damselflies Prodasineura autumnalis and Pseudagrion rubriceps. Several individuals of the large stream libellulid Zygonyx iris were observed soaring over the woodland behind Ho Pui village. This species breeds in clear, fast-running streams (see Wilson, 1995). Hydrobasileus croceus and Neurothemis tullia, in disused agricultural land at the upstream section, were other notable records.

 

Table 4.7

Odonates Observed in the Study Area

 

Ischnura senegalensis

Ceriagrion auranticum

Copera marginipes

Prodasineura autumnalis

Pseudagrion rubriceps

Brachydiplax chalybea

Orthetrum glaucum

Orthetrum luzonicum

Orthetrum pruinosum

Orthetrum sabina

Brachythemis contaminata

Crocothemis servilia

Diplacodes trivialis

Neurothemis tullia

Neurothemis fulvia

Pseudothemis zonata

Trithemis aurora

Trithemis festiva

Rhyothemis variegata

Tramea virginia

Hydrobasileus croceus

Pantala flavescens

Tholymis tillarga

Zygonyx iris

No. of species recorded: 24

 

 

(v)        Butterflies

 

A substantial total of fifty species were recorded across the extended study area (see Table 4.8). This is a significantly larger number of species than was recorded at KT2, KT4-7, KT12 and KT14-15 where a range of 9 – 26 species was recorded during the same time period with a similar survey effort (BBV, 2002). The most notable species recorded was Danaid Eggfly Hypolimnas misippus seen in disused agricultural land close to the pig farms at the southern end of the site. Some species more typical of woodland habitats, e.g. Cupha erymanthis, Cyrestis thyodamas, Discophora sondaica, Euthalia phemius, Faunis eumeus and Pantoporia hordonia and Melanitis leda were recorded in the patch of woodland close to the egretry.

 


Table 4.8

Butterfly Species Observed in the Study Area

 

Euploea midamus

Ideopsis similis

Elymnias hypermnestra

Lethe confusa

Lethe rohria

Melanitis leda

Mycalesis mineus

Ypthima baldus

Faunis eumeus

Discophora sondaica

Euthalia phemius

Cyrestis thyodamas

Charaxes bernardus

Ariadne ariadne

Athyma selenophora

Cupha erymanthis

Hestina assimilis

Hypolimnas bolina

Hypolimnas misippus

Junonia atlites

Kaniska canace

Neptis hylas

Pantoporia hordonia

Symbrenthia lilaea

Abisara echerius

Zemeros flegyas

Iraota timoleon

Acytolepis puspa

Famegana alsulus

Zizeeria maha

Zizina otis

Pieris canidia

Hebomoia glaucippe

Eurema blanda

Eurema hecabe

Graphium agamemnon

Graphium doson

Graphium sarpedon

Papilio bianor

Papilio demoleus

Papilio helenus

Papilio memnon

Papilio paris

Papilio polytes

Papilio protenor

Astictopterus jama

Erionota torus

Parnara guttatus

Polytremis lubricans

Potanthus confucius


(vi)       Aquatic Invertebrates

 

Aquatic invertebrates were not sampled due to heavily polluted state of the water.

 

(vii)      Fish

 

The surveys were conducted on 9th and 15th  May and 12th July 2000. No fish were observed.

 

                 Discussion

 

4.4.4                 All of the survey work reported above was undertaken on a limited time-scale in one season (summer), and therefore cannot purport to be a fully comprehensive record of the fauna likely to be present. In particular, seasonal birds are under-represented due to the survey timing, which has excluded most winter visitors and passage migrants. However, it is considered that the key concern with respect to avifauna is the potential impact on wetland dependent bird species, in particular the ardeids using the Ho Pui egretry. No additional pertinent data would have been gathered in this respect from a dry (winter) season survey. Accordingly, notwithstanding these caveats, the following observations can be drawn.

 

                 Birds

 

4.4.5                 The site is considered to be potentially of ecological importance for a breeding (or potentially breeding) bird species if it meets the following criteria:

 

                     It supports a breeding population of a species which occurred in less than 5% of 1 km grid squares in Hong Kong in the HKBWS breeding bird survey (Carey et al., 2001);

 

                     Or, it supports 5% or more of the Hong Kong breeding population of a species;

 

                     Or, it supports 1% or more of the Hong Kong population of a species for which the Hong Kong population is considered to be of global significance by Carey et al. (2001);

 

                     Or, it supports a significant population of a species which is declining in Hong Kong; the definition of “significant” in this context to be assessed on a species-by-species basis with reference to the relevant literature, in particular Fellowes et al. (2002) and Carey et al. (2001).

 


4.4.6                 Species of conservation importance or concern could be recorded in the Study Area, but in circumstances under which the Study Area population does not satisfy the above criteria. This applies, in particular, to wide-ranging species such as raptors where a casual observation does not indicate that the habitat over which the bird is passing is of any importance to the species. In the present study, this exclusion applies to raptors such as Bonelli’s Eagle and Crested Serpent Eagle which are species of mountains and forest respectively and would not make use of Study Area habitats to any significant extent.

 

4.4.7                 Another difficulty applies to species which are likely to be under-recorded during general surveys because they are cryptic or nocturnal. Such species include owls, which are usually only recorded at night (night-time surveys were not a requirement of the HKBWS breeding survey). Caution, has, therefore, to be applied in assessment of the conservation importance of cryptic species in order that undue importance is not attached to sightings of such species.

 

4.4.8                 As a further point, exotic species are not considered to be of conservation significance unless the population meets global threat criteria as defined in BirdLife (2000).

 

4.4.9                 Accordingly, Table 4.9 indicates those species of potential conservation concern recorded in the Study Area and highlights those which meet the foregoing criteria and are, therefore, of actual conservation concern with respect to this EIA.

 

Table 4.9

Bird Species of Potential and Actual Conservation Concern with respect to Their Use of the Study Area

 

Note: Those species of actual conservation concern (the presence of which is significant in determining the acceptability of the proposed development and for which appropriate mitigation measures should be entertained) for this EIA are shown in bold.

 

Species

Conservation concern criterion to be satisfied

Is criterion satisfied?

Little Grebe

Breeding population of a species occurring in less than 5% of 1 km squares in Hong Kong

No, already eliminated from the Study Area by habitat destruction.

Little Egret

Supports at least 5% of the Hong Kong breeding population of a species.

No, 4 prs. at Ho Pui is only 1.6% of 2000 Hong Kong breeding population.

Cattle Egret

Supports at least 5% of the Hong Kong breeding population of a species.

Yes, 18 prs. at Ho Pui comprises 27% of 2000 Hong Kong breeding population.

Chinese Pond Heron

Supports at least 5% of the Hong Kong breeding population of a species.

Yes, 6 prs. at Ho Pui is 5% of 2000 Hong Kong breeding population.

Bonelli’s Eagle

Breeding population of a species occurring in less than 5% of 1 km square in Hong Kong.

No, casual observation of a bird flying over does not indicate that the Study Area is of importance for this species.

Eurasian Hobby

Breeding population of a species occurring in less than 5% of 1 km squares in Hong Kong.

No, casual observation of a bird flying over does not indicate that the Study Area is of importance for this species.

Emerald Dove

Breeding population of a species occurring in less than 5% of 1 km squares in Hong Kong.

Yes, recorded in 4.3% of 1 km squares in Hong Kong, indicating requirement for semi-natural forest. However, potential habitat in the Study Area is remote from the development area.

Collared Scops Owl

Breeding population of a species occurring in less than 5% of 1 km squares in Hong Kong.

Yes, recorded in 4.5% of 1 km squares in Hong Kong. However, a nocturnal species which is probably much more widespread than HKBWS survey suggests.

White-throated Kingfisher

Declining as a breeding species in Hong Kong.

Yes, presence in suitable habitat suggests that it may breed in the Study Area.

Common Myna

Breeding population of a species occurring in less than 5% of 1 km squares in Hong Kong.

No, this is an exotic species with a huge global range.

 

 

4.4.10             Thus, as noted in Table 4.9, the bird species of conservation concern present in the Study Area are Cattle Egret and Chinese Pond Heron (breeding colony of importance), Emerald Dove and Collared Scops Owl (restricted breeding distribution in Hong Kong) and White-throated Kingfisher (declining in Hong Kong). However, Emerald Dove is unlikely to use any habitat close to the development area, whilst Collared Scops Owl probably only meets the conservation concern category because it is an elusive nocturnal species. Accordingly, the key species, the needs of which should be taken account when the acceptability of the proposed development is evaluated, are Cattle Egret, Chinese Pond Heron and White-throated Kingfisher. Since the Ho Pui egretry supported 27% of the Hong Kong breeding population of Cattle Egrets in 2000, any potential impacts on this species are of great concern.

 

                 Amphibians and Reptiles

 

4.4.11             Thirteen species of herpetofauna were recorded at KT13. Five of the six snake species encountered during the surveys were shared between the Ma On Kong and Ho Pui sites, including one species – Checkered Keelback Xenochrophis piscator – usually associated with wetland habitats.

 


4.4.12             Significantly, no obligate stream species (amphibian or reptile) were recorded, undoubtedly as a consequence of severe pollution and other anthropogenic disturbance at all sites. However, seasonal marshes are present at KT13, and due consideration should be given to protection of the area during stream channelization works at the site.

 

4.4.13             Sightings of herpetofauna within the KT 13 channel involved only one snake (Checkered Keelback Xenochrophis piscator). Channelization would remove refuges from the streams and therefore make them even less attractive for breeding amphibians. Rehabilitation of the rivers, by reduction or removal of major pollution sources (e.g. pig farms), would, conversely, lead to greater use by amphibians and perhaps eventual recolonization by obligate stream species such as Green Cascade Frog Rana livida.

 

4.4.14             With the exception of Checkered Keelback none of the reptile species encountered is particularly associated with wetland habitats.

 

                 Dragonflies & Damselflies

 

4.4.15             KT13 was rich in odonates (24 species). Obligate stream species were encountered in this channel (P. autumnalis, P. rubriceps and Zygonyx iris). The presence of these species at the heavily polluted KT13 may be attributed to non-breeding colonization from the nearby, slightly polluted, KT12.

 

4.4.16             Although some lowland dragonflies (e.g. Pantala flavescens, Brachythemis contaminata, Orthetrum sabina) can breed successfully in almost any body of water, many species require a specific substrate such as submerged vegetation, woody or weedy margins, or coarse gravel as oviposition site, and/or larval habitat, and partially submerged objects such as boulders or emergent vegetation as larval emergence sites (see e.g. Corbet, 1999). Insensitive channelization which resulted in removal of such substrates would therefore also remove many breeding odonates, including the seemingly ubiquitous Ischnura senegalensis, as well as more sensitive species.

 

                 Butterflies

 

4.4.17             Butterflies are not especially associated with wetland habitats. However they tend to be numerous and species-rich where floral diversity is high, and where woodland edge is a common element of the landscape. There were 50 species recorded in KT13 during the extended survey.

 

4.4.18             Only one rare species, Danaid Eggfly Hypolimnas misippus, was recorded during the surveys. This appeared to be an irruptive species during 2000 (G.T. Reels, pers. obs.).

 

Aquatic Invertebrates

 

4.4.19             KT13 was very badly polluted and hence aquatic invertebrates were not surveyed. However, it is reasonable to assume that aquatic invertebrate communities would show characteristics intermediate between those of the KT2 and KT7 streams  (see BBV (2002)).

 

4.4.20             It is highly likely that a reduction in the pollution load in the channels would lead to eventual re-colonization by pollution-sensitive species. River channelization, on the other hand, would inevitably lead to a loss of appropriate microhabitats (e.g. coarse gravel, boulders, trailing vegetation, and submerged woody material) for many invertebrate species, and a consequent decline in species diversity. Any deposits on the channel bottoms would be dominated by fine sediments and organic particles, which can clog the gills and feeding apparatus of some animals, as well as restricting water movement within the substrate, thereby reducing oxygen levels (Dudgeon & Corlett, 1994).

 

                 Fish

 

4.4.21             No fish were observed during the site visits. The streams are heavily polluted, making it impossible for fish fauna to survive.

 

                 Overall stream characteristics

 

4.4.22             Despite the stream itself being heavily polluted at the present time, the KT13 Study Area is a rare and ecologically significant lotic habitat, characterized by a gravel streambed and meandering platform; streams with this type of geomorphology are restricted to northern New Territories, which have been heavily impacted by pollution and, more recently, large-scale channelization. Channelization not only removes the unique habitat, it also swamps out all the aquatic fauna from this species rich habitat.

 

4.5                       Egretry and Flight-line Survey Results of Ho Pui and Ma On Kong Egretries

 

4.5.1                 A safe nest site is a fundamental requirement for successful breeding in birds. In colonial species such as ardeids (herons and egrets), pressure for breeding sites is thought to be a major factor influencing coloniality (Kushlan and Hafner 2000). Coloniality brings with it many ecological advantages such as predator avoidance and assistance in locating the most profitable food resources. With it also come potentially major disadvantages, not least of all vulnerability to disturbance or loss of the nesting site, which for local populations at least can have severe negative impacts.

 

4.5.2                 The purpose of this aspect of the study was to survey the two egretries that may be affected as part of the project, and to investigate foraging areas and habitats of the ardeids during the breeding season.

 

                 Egretry Surveys

 

4.5.3                 The Ho Pui and Ma On Kong egretries (Figure 4.3) were visited on 10th and 30th April, 22nd and 26th May, 22nd and 26 June and 1st and 16th July. Plate 4.15 and Plate 4.16 show the two egretries. Plate 4.17 shows a Chinese Pond Heron in the Ma On Kong Egretry. The data collected were compared to published data for the area, notably Young (1993), Young and Cha (1995), Carey (1998), and Wong et al. (undated).

 

4.5.4                 Results

 

(i)         Population size

 

A maximum of 42 pairs of egrets was present in the two egretries. Three species were found breeding Chinese Pond Heron Ardeola bacchus (20 pairs) Cattle Egret Bulbulcus ibis (18 pairs) and Little Egret Egretta garzetta (4 pairs). The details of these are given in Tables 4.10 and 4.11.

 

Table 4.10

Number of Pairs of Breeding Egrets at Ho Pui during Summer 2000

 

 

April

May

June

Maximum

Chinese Pond Heron

6

6

3

6

Little Egret

4

2

2

4

Cattle Egret

10+

18

8

18

No. of pairs

20+

26

13

28

 

Table 4.11

Number of Pairs of Breeding Egrets at Ma On Kong during Summer 2000

 

 

April

May

June

Maximum

Chinese Pond Heron

0

4+

14

14

Little Egret

0

0

0

0

Cattle Egret

0

0

0

0

No. of pairs

0

4+

14

14


(ii)        Brood Size

 

Brood sizes recorded at the two egretries are given in Tables 4.12 and 4.13.

 

Table 4.12

Brood Size and Frequency at Ho Pui Egretry during June 2000

 

Brood size

Chinese Pond Heron

Little Egret

Cattle Egret

1

0

0

0

2

0

0

2

3

3

3

5

 

4.5.5                 At least 47 Cattle Egret chicks or juveniles were noted on 22 June 2000, representing an average of 2.6 young per pair for 18 pairs.

 

Table 4.13

Brood Size and Frequency at Ma On Kong Egretry during June 2000

 

Brood size

Chinese Pond Heron

1

0

2

0

3

5

 

4.5.6                 At least 40 young were present on 22 June 2000, representing an average of 2.85 young per pair for 14 pairs.

              

Discussion

 

                 Population Size

 

4.5.7                 Combined, the two egretries at Ma On Kong and Ho Pui accounted for 27% and 16% of the Hong Kong breeding population for Cattle Egret and Chinese Pond Heron respectively in 2000 (Kwok et al., 2001). The percentage of the Little Egret breeding population was, however, only 2%. The Hong Kong population of Chinese Pond Heron is of global importance, and that of Little Egret may be of regional importance (Carey and Young, 1998).

 

4.5.8                 Numbers of breeding pairs of egrets increased at both Ho Pui and Ma On Kong during 2000. At Ho Pui, this ended the decline noted there since 1997 (Figure 4.4). However, the long-term decline of Chinese Pond Heron continued, although there was a slight increase during 2000, the six pairs breeding are considerably lower than the peak of 32 in 1991. The overall increase in 2000 was due to higher Cattle Egret numbers, which were close to the peak of 22 pairs in 1997.

 

Figure 4.4

Number of Pairs of Egrets Breeding at Ho Pui during 1991-2000

 


4.5.9                 At Ma On Kong, numbers of breeding egrets increased by 50% during 1999 (Figure 4.5). Only Chinese Pond Heron breeds at Ma On Kong, and although both Cattle Egret and Little Egret bred in 1995, they have not since. Numbers of Chinese Pond Herons have increased steadily since 1997, although there was a marked drop from 12 to 3 pairs between 1996 and 1997.

 

Figure 4.5


Number of Pairs of Egrets Breeding at Ma On Kong during 1995-2000

 

 

4.5.10             The increase in numbers of Chinese Pond Herons at Ma On Kong may in part explain the decrease at Ho Pui, although even if the numbers at the two egretries are combined there are marked fluctuations overall, indicating additional factors. However, as can be seen from Figure 4.6, in recent years combined numbers of pairs of Chinese Pond Herons breeding at Ma On Kong and Ho Pui have been more stable.

 


4.5.11             A new egretry found at Kam Tin Shui Mei (grid reference 974856 on Lands Department Map HM20C) during summer 2000 may also be of influence. At least 14 pairs of Chinese Pond Heron were present at this egretry during 2000 (Table 4.14). The age of the Kam Tin Shui Mei egretry is not known, and it is impossible to determine whether Chinese Pond Herons breeding there originated from Ho Pui. It is notable that at 34 pairs, the number of Chinese Pond Herons breeding at all three egretries in the Kam Tin Valley in 2000 is only two pairs greater than the peak of 32 pairs at Ho Pui in 1991 (Figure 4.6).

 

Table 4.14

Number of Pairs of Breeding Egrets at Kam Tin during Summer 2000

 

 

April

May

June

Maximum

Chinese Pond Heron

nc

14

12

14

Little Egret

nc

2

2

2

Cattle Egret

nc

0

0

0

No. of pairs

nc

16

14

16

nc = not counted

 

Figure 4.6


Numbers of Chinese Pond Herons Breeding at Ho Pui, Ma On Kong and Kam Tin Shui Mei during 1991-2000

 

 

4.5.12             Unfortunately, no data exist on breeding success for previous years for the three egretries covered here. However, limited details of breeding success given in Wong et al. (undated) at other egretries in Hong Kong are of interest in this context. A summary of these is given in Table 4.15.

 


Table 4.15

Summary of Brood Size in Hong Kong Egretries during 1999

(after Wong et al. undated).

 

Brood size

Chinese Pond Heron

Little Egret

Cattle Egret

1

3

23

1

2

0

26

0

3

1

12

0

4

0

1

0

 

4.5.13             While these results are not directly comparable, they do indicate that the breeding success at the three egretries under investigation was high during 2000.

 

4.5.14             Cattle Egrets are less piscivorous than other egrets; they primarily feed on insects, amphibians and reptiles (Voisin, 1991). As such they prefer freshwater wetlands to saline or brackish habitats (Wong et al., undated). Food availability is a major factor influencing chick mortality, with starvation being noted in some studies as the major cause of mortality in Cattle Egret chicks (Siegfried, 1972). The direct affects of weather on chick mortality in Hong Kong are unknown, but are likely, in some years at least, to be significant.

 

                 Environmental Factors Influencing Utilization

 

4.5.15             Some nests sites have apparently been lost in the past year through clearance of bamboo for the construction of village houses (R. Fan pers comm. to P. J. Leader). In addition, the invasive exotic creeper Mikania micrantha appeared to be colonizing parts of the main egretry. This species has been known to cause sections of other egretries in Hong Kong to become abandoned (Young and Cha, 1995), and is potentially a serious problem.

 

                 Summary

 

4.5.16             There was an increase in numbers of breeding ardeids at both Ho Pui and Ma On Kong during 2000. A further egretry was located at Kam Tin Shui Mei during the summer. Results of surveys from all three egretries indicate high breeding success. It is suggested that the 2000 breeding season was generally good for egrets, and that the increase in number of egretries in the northwest New Territories may not indicate a long term increase in the local breeding population.

 

4.5.17             Studies elsewhere (Hafner, 2000) have identified the potential for disturbance at egretries to have a severe negative impact on breeding success, and in order to reduce this likelihood, a buffer area of 100 m from the egretries where construction works should not take place is recommended for the period April to September. The location of the buffer area is shown on Figure 4.13.

Changes in numbers and distribution of egretries during 2000 - 2005

 

4.5.18             Since a period of five years has elapsed since the egretry survey data was collected, the following updated information has been added detailing changes in the numbers and distribution of breeding egrets during the period 2000 – 2005 (Sources: Hong Kong Bird Watching Society Egretry Counts and Asia Ecological Consultants Ltd. unpubl. data).

 

Table 4.16

Number of Pairs of Breeding Egrets at Ho Pui 2000 - 2005

 

 

2000

2001

2002

2003

2004

2005

Chinese Pond Heron

2

2

1

0

3

0

Little Egret

2

2

2

0

1

0

Cattle Egret

9

5

17

12

9

0

Total

13

9

20

12

13

0

 

Table 4.17

Number of Pairs of Breeding Egrets at Ma On Kong 2000 - 2005

 

 

2000

2001

2002

2003

2004

2005

Chinese Pond Heron

6

5

12

17

15

16

Little Egret

0

0

0

0

0

0

Cattle Egret

0

0

0

0

0

0

Total

6

5

12

17

15

16

 

Table 4.18

Number of Pairs of Breeding Egrets at Kam Tin Shui Mei 2000 - 2005

 

 

2000

2001

2002

2003

2004

2005

Chinese Pond Heron

15

11

0

0

0

0

Little Egret

1

3

0

0

0

0

Cattle Egret

0

3

0

0

0

0

Total

16

17

0

0

0

0

 

Table 4.19

Number of Pairs of Breeding Egrets at Tung Shing Lei (Au Tau) 2000 - 2005

 

 

2000

2001

2002

2003

2004

2005

Chinese Pond Heron

7

3

5

7

19

37

Little Egret

21

6

27

16

38

52

Cattle Egret

0

0

0

0

0

13

Total

28

9

32

23

57

102

 

 

 

 

Table 4.20

Total Number of Pairs of Breeding Egrets in the Kam Tin Area 2000 - 2005

 

 

2000

2001

2002

2003

2004

2005

Chinese Pond Heron

30

21

18

24

37

53

Little Egret

22

5

29

16

39

52

Cattle Egret

9

8

17

12

9

13

Total

61

34

64

52

85

118

 

4.5.19             The main trend in egretry distribution over the past six years is the concentration of breeding pairs at Tung Shing Lei, which was first utilized in 2000, since 2004. Meanwhile, the egretry at Shui Mei was abandoned in 2001 and that at Ho Pui was deserted in 2005, whilst the number of pairs at Ma On Kong showed an increase in 2002 and has since remained stable.

 

4.5.20             The increase in the importance of the Tung Shing Lei egretry has been accompanied by an increase in numbers of Chinese Pond Herons and Little Egrets, but not of Cattle Egrets. Numbers of this species have fluctuated between eight and 17 pairs, with no clear trend. Cattle Egrets were the main species utilizing the Ho Pui egretry during 2000 – 2004, and it seems likely that in 2005 the birds which formerly nested at Ho Pui moved to Tung Shing Lei, which was utilized by Cattle Egrets for the first time that year.

 

4.5.21             The reason for the abandonment of the Ho Pui egretry in 2005 is not certain. Abandonment of egretries in Hong Kong has usually been attributed to a loss of wetland habitat, disturbance or colonization of the nest trees by climbing plants (Young and Cha 1995). There was no observed change to the trees forming the egretry between 2004 – 2005 and no apparent increase in disturbance. However, a change in land use in this part of the Kam Tin valley may be responsible; some of the nearby agricultural fields utilized by foraging Cattle Egrets in 2004 were planted with maize in 2005, making them unsuitable for use by egrets (J. Allcock, pers. obs.).

 

4.5.22             Historically, there has been a pattern of rather frequent changes in location of egretries in Hong Kong (e.g. Young and Cha 1995, Wong and Woo 2004). Young and Cha (1995) found no cases where an egretry that was abandoned was re-occupied in subsequent years, and no such re-occupation has been noted during the period from 1995 – 2005 (M.R. Leven pers. obs., Wong and Woo 2004). There is, therefore a significant possibility that the Ho Pui egretry will be permanently abandoned.

 

                 Flight Line Surveys

 

4.5.23             A common method of investigating feeding habitat use by ardeids involves following their flight lines. Individual egrets are observed as they leave the colony and land at their feeding sites. This methodology has been used in a number of studies in Hong Kong (Young 1993, Cornish 1996, Wong 1990, and Wong et al. undated). It is not always possible to follow all individuals, as many are lost from sight. It is possible to follow up on birds lost from sight by identifying habitats being utilized by egrets in the direction of lost birds. However, the results of this approach may be biased towards larger feeding areas that contain higher numbers or densities of birds, or habitats where birds spend longer though they are not foraging. Using this method it is easy to over-estimate the importance of some areas and thus possibly some habitats (Young, 1993).

 

4.5.24             In this project, investigation of flight lines has been used to address specific questions relating to habitat type and location of the foraging areas of breeding adults at the two egretries. This information was considered essential to establish whether the construction works to be undertaken would impact upon the breeding egrets through habitat loss, or disturbance of foraging areas. Disturbance of the breeding sites is dealt with elsewhere.

 

4.5.25             Flight line observations were undertaken on 29th May, 3rd, 14th and 23rd June and 1st July 2000. On this later date, it was clear that many birds had left the egretry as the majority of the young had fledged.

 

                 Results

 

4.5.26             During the fieldwork, exactly 200 individual egrets were followed as they left either Ho Pui or Ma On Kong. Most birds (89%) were from Ho Pui, and related to Cattle Egret, Little Egret, Chinese Pond Heron, and Night Heron. Further details are given for all species except for Night Heron, which related to a single individual on one date, and was not recorded during the breeding surveys.

 

(i)         Distance flown

 

Details of distance flown by the birds followed are given in Table 4.21.

 

Table 4.21

Details of Distances Flown by Egrets at Ho Pui and Ma On Kong Egretries,

Summer 2000 (All measurements in meters)

 

All birds

Little Egret

Cattle Egret

Chinese Pond Heron

Chinese Pond Heron

(Ho Pui only)

Chinese Pond Heron (Ma On Kong only)

Minimum

80

500

150

80

80

200

Maximum

5700

4700

5700

4040

4040

2900

Average

2178.5

1640.9

2471.6

1317.4

1544.2

1187.0

s.d.

1218.9

1091.7

1216.6

787.3

1075.1

643.2

n.

199*

22

137

40

18

22

*excludes a single Black-crowned Night Heron

 

4.5.27             The number of individual egrets in each 100 m band radiating out from the egretry was also calculated. These data are presented in Figure 4.7.

 

Figure 4.7

Distance from Egretry (m), and Number of Birds for Ho Pui and Ma On Kong,


Summer 2000.

 

              

 (ii)       Flight Direction

 

                             Direction of flight was divided into 8 sectors, and this was further sorted into distance (Figure 4.8) following Young (1993). Data for each species, with those data for Chinese Pond Heron separated for the two egretries, are given in Figures 4.9 to 4.12.

 

(iii)       Habitat Selection

 

                             Of the birds followed, habitat selection was noted for 45%. The remainder either were lost from sight, or landed at a location where it was not possible to determine the habitat (as this was obscured, often by buildings). Details of habitat selection are given in Table 4.22.

 

Table 4.22

Habitat Selection of Egrets at Ho Pui and Ma On Kong Egretries, Summer 2000.

 

 

All birds

Little Egret

Cattle Egret

Chinese Pond Heron

Active dry agriculture

1 (1%)

0 (0%)

0 (0%)

1 (4%)

Active wet agriculture

39 (43%)

3 (60%)

21 (32%)

17 (74%)

Inactive wet agriculture

36 (40%)

1 (20%)

33 (51%)

3 (13%)

Grass

8 (9%)

0 (0%)

8 (12%)

0 (0%)

Trees

6 (7%)

1 (20%)

3 (5%)

2 (9%)

Total

90 (100%)

5 (100%)

65 (100%)

23 (100%)

 

 

                 Discussion

 

                 Distance Flown

 

4.5.28             As can be seen from Figure 4.7, there was a peak of distance flown from the egretry at about 800 m. Below this distance numbers were very low and there was a general increase (although with marked fluctuations) between 1000 m and 3000 m. The distance 1000 to 3000 m accounted for 62.6% of all flights. It is therefore of potential concern that all of the proposed drainage channels at KT13 and KT12 also fall within this range, with implications on habitat loss, and construction disturbance, of foraging areas.

 

                 Flight Direction

 

4.5.29             Flight direction was concentrated within the NNE and ENE sectors (Figure 4.8) for all three species breeding at Ho Pui, and within the ENE and SEE sectors for the Chinese Pond Herons breeding at Ma On Kong. At Ho Pui, the NNE and ENE sectors accounted for 45% of Little Egrets, 75% of Cattle Egrets, and 83% of Chinese Pond Herons. At Ma On Kong, the ENE and SEE sectors accounted for 68% of the Chinese Pond Herons breeding there.

 

4.5.30             Given that both egretries lie at the southwest end of a northeast-southwest orientated valley, which has shrub-covered hills to the south and west, and wetlands to the north and east, it is not surprising that the northeast holds the main foraging areas. However, it is again of note that the proposed works for KT12, KT13, KT14 and KT15 are either north to east from Ho Pui or northeast to south east from Ma On Kong, i.e. within the preferred sectors at both.

 

                 Habitat Selection

 

4.5.31             The importance of wet agricultural areas, as foraging sites for the egrets breeding at Ho Pui and Ma On Kong are apparent from Table 4.17. Active and inactive wet agriculture accounted for 83% of the habitat selected by all birds. It was in fact similar for all three species: 80% for Little Egret, 83% for Cattle Egret and 87% for Chinese Pond Heron. There were differences in utilization of active and inactive wet agriculture, with both Little Egret and Chinese Pond heron preferring active wet agriculture, and Cattle Egret preferring inactive wet agriculture.

 

4.5.32             Rivers, creeks and drainage channels have been recorded as foraging areas for ardeids in similar Hong Kong studies. Young (1993) found that up to 37% of Chinese Pond Herons at Tsim Bei Tsui and up to 22% at Mai Po foraged in nullahs. Wong (1991) found creeks to be the second most important habitat for Little Egrets after fishponds at Mai Po. The reason for the absence of sightings of birds using streams in the present study may simply be a consequence of the relatively small number of observations. It is also possible that some of the birds lost from sight during the observations were foraging within the areas to be channelized. However, it may be that other factors (for example stream width, substrate, adjoining vegetation, pollution and disturbance) resulted in the streams in the Study Area genuinely being little used by ardeids. Nevertheless, on a precautionary basis, it is suggested that since Chinese Pond Herons have frequently been observed using streams elsewhere in Hong Kong, direct disturbance to the KT13 stream should be minimized.

 

                 Summary

 

4.5.33             The flight line data showed that the preferred areas of foraging ardeids were also those where KT12 and KT13 are to be constructed. Whilst it appears that birds make little use of the KT13 stream for foraging, other Hong Kong studies have demonstrated the importance of streams for feeding Chinese Pond Herons. Accordingly, on a precautionary basis, loss of potential feeding habitat (i.e. a natural stream bottom) in KT13 should be avoided. The works program should avoid any construction works in key feeding areas and in KT13 (existing stream course) next to the Ho Pui Egretry site during the period from April to September.

 

 


Figure 4.8

Flight Direction and Distance Flown from the Egretry


Figure 4.9

Direction of Flight and Distance Traveled for Little Egret

 

Little Egret (n=21)

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 


Note: Underlined figures are total for that sector.

 

 

 

 

 

 

Figure 4.10

Direction of Flight and Distance Traveled for Cattle Egret

 

Cattle Egret (n=137)

 

 

Note: Underlined figures are total for that sector.

 

Figure 4.11

Direction of Flight and Distance Traveled for Chinese Pond Heron

 

Chinese Pond Heron (Ho Pui) (n=18)

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 



Figure 4.12

Direction of Flight and Distance Traveled for Chinese Pond Heron

 

Chinese Pond Heron (Ma On Kong) (n=22)

 

 

 

 



4.6                       Ecological Evaluation of Different Habitats

 

4.6.1                 The site (KT13) is generally an important area, supporting good communities of birds, herpetofauna, dragonflies and butterflies. Until 2005 the most important ecological feature of the stream was the presence of the egretry to the east of Ho Pui village. The egretry was not occupied in 2005 but it is not possible at this point to state whether or not it has been permanently abandoned. Tables 4.23 - 4.33 provide an evaluation of the ecological value of the eleven habitats within the Study Area.

 

Table 4.23

Ecological Evaluation of Woodlands

 

Criteria

Ma On Kong

Ho Pui

Naturalness

Mainly natural but  modified by afforestation

Semi-natural

Size

Large (26.08 ha)

Small (0.61 ha)

Diversity

High

Moderate

Rarity

Not rare

Not rare

Re-creatability

Re-creatable in long term (over 30 years)

Re-creatable in long term (over 30 years)

Fragmentation

Continuous

Fragmented by footpaths, roads

Ecological linkage

Connected with the Tai Lam Country Park

Adjacent to the Ho Pui Egretry

Potential value

High

High if the egretry is re-occupied

Nursery/breeding ground

The woodland potentially provides a breeding ground for birds, butterflies, and reptiles.

Until 2005 the woodland contained an egretry which was an important nursery and breeding ground for Cattle Egret. Little Egret and Chinese Pond Heron were also recorded as breeding there. The woodland potentially provides a breeding ground for other birds, butterflies and reptiles.

Age

Over 40 years

Over 40 years

Abundance/ richness of wildlife

The woodlands contain moderate species richness.

The woodlands contain moderate species richness.

Ecological value

Moderate - high

High in area occupied by egretry, otherwise moderate

 


Table 4.24

Ecological Evaluation of Shrublands

 

Criteria

Ma On Kong

East of Route 3

Naturalness

Natural

Mainly natural but with little modification by grave worshippers

Size

Moderate within the Study Area (4.5 ha)

Moderate (9 ha)

Diversity

Moderate

Moderate

Rarity

Not rare

Not rare

Re-Creatability

Readily re-Creatable

Readily re-Creatable

Fragmentation

Continuous

Lightly fragmented by some footpaths

Ecological linkage

Connected with the Tai Lam Country Park

Some linkage with woodland

Potential value

Moderate

Moderate

Nursery/breeding ground

Moderate value

A potential breeding ground for birds, reptiles and insects..

Age

At an early successional stage, the habitat is young

At an early successional stage, the habitat is young

Abundance/ richness of wildlife

Moderate

Moderate

Ecological value

Low - moderate

Low - moderate

 

Table 4.25

Ecological Evaluation of Marsh

 

Criteria

Remarks

Naturalness

May be derived from abandoned agricultural fields

Size

Small (1.18 ha)

Diversity

Low to moderate floral diversity but moderate to high in terms of wildlife supported

Rarity

Not rare, but becoming rarer

Re-creatability

Can be re-created within a short time for such young marsh

Fragmentation

No fragmentation

Ecological linkage

Close to the Ho Pui Egretry and provides suitable feeding conditions for breeding egrets

Potential value

Moderate

Nursery/breeding ground

The marsh is potential breeding ground for birds, reptiles and insects.

Age

Young

Abundance/ richness of wildlife

Moderate abundance

Ecological value

Moderate

 

Table 4.26

Ecological Evaluation of Fishponds

 

Criteria

Remarks

Naturalness

Man-made habitat

Size

Small (2.3 ha)

Diversity

Low habitat diversity but high in terms of wildlife supported

Rarity

Not rare, but becoming rarer

Re-creatability

Can be re-created artificially

Fragmentation

-

Ecological linkage

Some ponds are adjacent to the egretry

Potential value

Ponds at egretry are of high value

Nursery/breeding ground

The ponds are potential breeding grounds for birds and insects

Age

No information is available

Abundance/ richness of wildlife

Moderate

Ecological value

Moderate

 

Table 4.27

Ecological Evaluation of Stream (KT13)

 

 

Criteria

Remarks

 

Naturalness

Natural

 

Size

Moderate (about 1km in length within the Study Area, 3 ha)

 

Diversity

Moderate

 

Rarity

Not rare but lowland unchannelised streams rapidly becoming rarer

 

Re-Creatability

Re-creatable

 

Fragmentation

The stream is continuous but the path of the section with the West Rail Working Site is being changed

 

Ecological linkage

The stream passes through the egretry location

Potential value

The site has potential as a relatively ecologically important area, if the pollution load in the stream can be brought down.

 

 

Nursery/breeding ground

Prior to 2005, an important breeding ground for egrets and Chinese Pond Heron, as well as invertebrates (including dragonflies and butterflies), amphibians, reptiles and common fish species.

 

Age

Old (over 50 years)

 

Abundance/ richness of wildlife

High abundance.

 

Ecological value

Moderate overall, high in vicinity of the egretry (if egretry present)

 

 


Table 4.28

Ecological Evaluation of Low-lying Grasslands/Fallow Land

 

Criteria

Remarks

Naturalness

Derived from agricultural lands

Size

Small to moderate (from 17.05 ha)

Diversity

Low to moderate

Rarity

Common

Re-creatability

Re-creatable within a short time (1 to 2 years)

Fragmentation

Fragmented by footpaths, local roads

Ecological linkage

Adjacent to woodland, streams, ponds, shrubland and orchard

Potential value

Some area of this habitat are of higher value as they are adjacent to the egretry

Nursery/breeding ground

Potential breeding ground for reptiles, amphibians and insects.

Age

Young

Abundance/ richness of wildlife

Moderate

Ecological value

Moderate

 

Table 4.29

Ecological Evaluation of Hillside Grasslands

 

Criteria

Remarks

Naturalness

Natural

Size

Moderate to large in size within the Study Area (29.44 ha)

Diversity

Low

Rarity

Not rare

Re-creatability

Easily re-creatable naturally or artificially within 1 to 2 years

Fragmentation

Continuous

Ecological linkage

Connected with the Tai Lam Country Park

Potential value

Low but can be improved if hill-fire ceases and succession is allowed

Nursery/breeding ground

Low value

Age

Relatively recent

Abundance/ richness of wildlife

Low

Ecological value

Low

 

 


Table 4.30

Ecological Evaluation of Agricultural Lands

 

Criteria

Remarks

Naturalness

Man-made habitat for crop production

Size

Small to large (from 13.32 ha)

Diversity

Low

Rarity

Widespread

Re-creatability

Re-creatable artificially

Fragmentation

Fragmented by footpaths, roads, and other areas of urban environment such as villages

Ecological linkage

May act as movement corridors and foraging habitat for animals from woodlands nearby

Potential value

Low, but can be higher by applying some management practice to enhance the habitat heterogeneity

Nursery/breeding ground

Not important

Age

From recent to old

Abundance/ richness of wildlife

Low

Ecological value

Low

 

Table 4.31

Ecological Evaluation of Orchard/Horticultural Land

 

Criteria

Remarks

Naturalness

Man-made habitat

Size

Small (4.66 ha)

Diversity

Low

Rarity

Not rare

Re-creatability

Can be re-created artificially

Fragmentation

Fragmented by footpaths, roads

Ecological linkage

May provide foraging habitat for birds

Potential value

Low

Nursery/breeding ground

Feeding ground for birds and invertebrates. One patch of litchee orchard at Ma On Kong contains an egretry which is an important nursery and breeding ground for Chinese Pond Herons.

Age

From recent to old

Abundance/ richness of wildlife

Moderate abundance but generally very common and widespread species

Ecological value

Generally low, but moderate in the case of the litchee orchard at Ma On Kong used as an egretry.

 

 


Table 4.32

Ecological Evaluation of Urban

and Industrial Area(UIA)/Bare Ground/Works in Progress

 

Criteria

Remarks

Naturalness

Man-made habitat with heavy disturbance from human activities

Size

Small to large (72.84 ha)

Diversity

Very low

Rarity

Not rare

Re-creatability

Artificially re-creatable

Fragmentation

Fragmented within the Study Area

Ecological linkage

None

Potential value

Very low

Nursery/breeding ground

Not important

Age

From recent (Route 3) to old (Ma On Kong village)

Abundance/ richness of wildlife

Very low

Ecological value

Very low

 

Table 4.33

Ecological Evaluation of Drainage Channel

 

Criteria

Remarks

Naturalness

Man-made habitat with heavy disturbance from human activities

Size

Small (2.63ha)

Diversity

Very low

Rarity

Not rare

Re-creatability

Artificially re-creatable

Fragmentation

Not particularly fragmented

Ecological linkage

None

Potential value

Very low

Nursery/breeding ground

Not important

Age

Recent 

Abundance/ richness of wildlife

Very low

Ecological value

Very low

 

 


4.7                       Potential Ecological Impacts

 

                 Identification of Ecological Impacts

 

4.7.1                 This section identifies all potential impacts caused by the unmitigated channelization works within the Study Area during the construction and operation phases. The next section will evaluate these ecological impacts.

 

                 Construction Impacts

 

4.7.2                 Activities during the construction phase include site clearance, site formation, dredging, construction of the bypass culvert, paving of access road, etc. These are likely to have the impacts described below on fauna and flora species and the habitats in which they live.

 

(i)         Habitat Loss /Damage (Direct Impacts)

 

The direct impact of site clearance works on the existing stream channel is removal of riparian vegetation, loss of natural banks with woody or weedy margins and loss of substrate including submerged vegetation and/or coarse gravel. There will therefore be a direct impact on vegetation and non-vagile animal groups, notably invertebrates and amphibians. There will also be direct habitat loss for all other animal groups using the stream corridors, notably birds, amphibians, reptiles and dragonflies (which have vagile adults but non-vagile larvae).

 

The project will result in the direct permanent loss of habitats within the project site area as detailed in Table 4.34 below.

 

Table 4.34

Direct habitat loss arising from construction of the secondary drainage channel KT13

 

Habitat

Area (ha)

Ecological value of habitat

Bare ground

0.133

Very low

Fishpond

0.083

Moderate

Low-lying grassland / Fallow land

0.781

Moderate

Marsh

0.009

Moderate

Orchard / Horticultural land

0.687

Low

River / Stream

1.000

Moderate

Urban / Industrial area

0.380

Very low

Woodland

0.008

Moderate (because egretry not affected)

Total

3.081

 

The area of moderate value habitat to be impacted is about 1.881 ha. This comprises a very small area of fishpond, woodland and marsh and larger areas of low lying grassland/fallow land as well as the stream itself. The woodland area which would be lost does not form part of the area occupied by the egretry prior to 2005.  It is located at the eastern bank of the meander outside the CA zone (Figure 4.1). Whilst the woodland at Ho Pui as a whole is considered to be of high ecological value if the eg